The objectives of this proposal are the synthesis and evauation of novel selective inhibitors of steroid-transforming enzymes. Some of these steroid analogs are designed as active site-directed irreversible inhibitors of 3beta-and (3 and 17) beta-hydroxysteroid dehydrogenases as well as processes involved in the oxidative degradation of lanosterol and of cholesterol. Others are intended to be reversible inhibitors of these enzymes. The mechanisms by which enzyme inhibitiion occurs will be studied. These inhibitors may be of value not only in studies of enzyme action but as potential therapeutic agents in hormone-dependent diseases and in hypercholesterolemic states.